Having fought in four weight classes, boxer Floyd Mayweather Jr. has never lost a fight.

He retired in 2017 with a record of 50-0.

For his accomplishments in the ring, he has become a symbol of durability, resilience and will power.

So it made sense for Mayweather to accept an invitation from Camp Simcha in Glen Spey to spend the day with its campers who are fighting cancer and other chronic illnesses.

"That was completely awesome," one child said after Mayweather's rally in the camp's activity center. "It was the best time of my life."

Children come to Camp Simcha or one of its sister camps from around the world each summer.

Mayweather came to the camp for a surprise visit to inspire the children to keep fighting.

"I'm proud of you all," he said to the crowd at the activity center. "I want everyone in this room to stay positive and have great energy ... We need to stay behind them and help them, and let them know they're great and that anything is possible."

Ahead of Mayweather's visit Wednesday, some campers toured News 12 around the camp, showing that grand surprises like Mayweather's visit are simply part of the program at Camp Simcha.

Each day, camp counselors plan a fun surprise for the children.

"We live it up the whole summer," camper Avi Epstein said.

Esptein, who has been fighting cancer, was happy to show News 12 some of the camp, including Wednesday's life-size Monopoly installation.

"Even though you're going through hard times, you still have to push through," Epstein said. "Don't be embarrassed. It's the greatest camp. You'll have fun and fight through your disease, whatever you have."

When asked whether the camp's positive, action-packed climate improves patients' abilities to fight disease, Camp Oncologist Dr. Joseph Oved replied that the children truly seem to live for the camp.

"We've had kids who are dying," Oved said, "and their last final wish is, 'can I go to camp one more time?'"

Following the rally in the activity center, Mayweather held a boxing clinic in the camp gym.